Wiktionary
fourth official
n. (context soccer English) The official who keeps things at the dugout in order, and displays substitutions and the amount of injury time
Usage examples of "fourth official".
He was the fourth official who had served her in this post, and the only one who had not been shipped back to Constantinople within a week.
The fourth official grasped the lid of the chest and swung it open, exposing its contents for all to see.